A regular visitor, small numbers of Black-throated Divers can be found in favoured West and North coast bays from late October to mid April. Smith, in 1878, noted the species as much less common than either Red-throated or Great Northern Diver.

The first reports usually occur towards the end of October with the majority of sightings being in January and February, presumably of birds displaced from further north by either adverse weather or feeding conditions. An increase in reports in late March early April will be birds moving north from the Bay of Biscay. Large scale Spring movements have been reported from Finisterre and these are believed to involve part of the significant Scandinavian population.

The status of the species has changed in recent years with reports now consisting almost entirely of single birds. In the early eighties groups of up to six would congregate offshore from Pulias in February and March. These birds would occasionally commence display behaviour including vocalisations. An extraordinary record was of a summer plumage bird in Grande Havre from 22nd July to the 7th August 1996.